The present invention relates to a process for producing granulated organic matters by use of fermentation waste fluids treated by addition of methane fermentation materials. These granulated organic matters are useful as organic fertilizers.
Because fermentation waste fluids are rich in fertilizer components such as nitrogen, phosphoric acid and potassium and in organic matters necessary for plant growth, such as sugars, amino acids and vitamins they are useful as raw materials of fertilizers, but if concentrated at high concentration, they turn into materials with extremely high stickiness or viscosity due to the influence of high molecular weight organic matters such as polysaccharides derived from molasses etc. contained in fermentation waste fluids.
Production of organic fertilizers using such fermentation waste fluids suffers from problems resulting from said stickiness, such as occurrence of scaling at the time of drying, incapability of granulation.
Heretofore, a wide variety of techniques of reducing the stickiness of fermentation waste fluids have been examined. Examples include a method of adding mineral acids and subsequent heating (Japanese Published Examined Patent Application No. 16332/69), a method of mixing with chicken droppings (Japanese Published Examined Patent Application No. 12243/70), a method of adding lime and subsequent drying (Japanese Published Unexamined Patent Application No. 121060/75), and a method of drying fermentation waste fluid along with silicate (Japanese Published Unexamined Patent Application No. 167292/89).
However, the prior art techniques are practically unrealistic methods because of drawbacks such as complicated processes and inferior productivity, occurrence of smells at the time of drying, etc. or industrially disadvantageous techniques because fertilizer components are rendered scarce by use of additives which is unnecessary as fertilizer components.
At present, there is employed a method (referred to hereinafter as sulfuric acid addition method) which involves adding conc. sulfuric acid to concentrated fermentation waste fluid from molasses (concentration of sulfuric acid: 10to30%), then heating it for several hours (temperature: 100 to 105.degree. C.) thus converting soluble organic matters (sugars etc.) in the waste fluid into humus substance to improve physical properties, and drying and solidifying it (Japanese Published Unexamined Patent Application No. 18657/74). However, this sulfuric acid addition method requires enormous costs for facilities etc. in order to carry out the step of treatment with sulfuric acid, so there is demand for an economical process for producing physically stable granulated organic matters.